Chances are, you already know that diet soda is too good to be true. With that sweet taste and zero calories, something’s gotta give. And chances are, it’s your waistline and your health.In fact, study after study shows that diet soda is likely failing you in its pounds-free promise and putting your health at risk at the same time.Researchers have linked drinking diet soda with:Weight gainDiet soda drinking correlates with both increased waist circumference and a heightened body mass index. What’s up? One possible explanation is that diet soda disrupts our ability to feel full. Scientists have found that, at least in rats, having something artificially sweetened before a meal leads to greater food consumption at chow time. In general, sweet tasting foods and drinks appear to increase our appetite.RESEARCH: Fake Sugars Cause Weight GainHigher sugar consumption“The intense sweetness of these products primes the brain to want more of the regular sweeteners, ” says Lora Sporny, adjunct associate profession of nutrition and education at Columbia University Teachers College.Artificially sweetened drinks activate our sweetness response, but don’t completely satisfy it, leaving you craving more of the real thing. This can drive us to eat more sugary foods than we would normally.Kidney problemsJulie Lin, M.D., a kidney specialist at Brigham and Women’s Hospital in Boston, studied the soda habits and kidney health of more than 3,000 women for 11 years.“What we observed,” Dr. Lin says, “was an association between drinking two or more servings of diet soda per day and faster kidney function decline.” In fact, the kidneys of diet soda drinkers declined at three times the rate typical of aging.You don’t want to mess with your kidneys, notes Lin. “They’re really one of the most important organs for keeping our whole body in balance in terms of processing the waste that the body generates just from our daily food intake,” she says. Even just moderate kidney decline goes hand-in-hand with an increased risk for cardiovascular disease.MORE: Should There Be a Diet Soda Tax?Increased diabetes risk“If you’re a consumer of diet soda, you have a higher risk of developing metabolic syndrome than a non-consumer,” says Lyn Steffen, Ph.D., R.D, a professor in the division of epidemiology and community health at the University of Minnesota.Here’s why that’s bad news: Metabolic syndrome involves a deadly combination of abdominal obesity, elevated blood pressure, low HDL cholesterol, high triglycerides (fatty acid derivatives linked to heart disease and stroke) and elevated glucose (high blood sugar)—all of which increases the risk of diabetes, coronary heart disease and stroke.Steffen studied thousands of people over nine years. At the end of the study, she looked at the study subjects’ diets and whether they had developed metabolic syndrome. She found that the greatest predictors of someone getting the syndrome were those who consumed meat-heavy diets, fried foods and diet soda. Other researchers have linked diet soda drinkers with a 67 percent greater risk of developing full-fledged type 2 diabetes.MORE: Which Sweeteners Are Bad For You?StrokeA January 2012 study in the Journal of General Internal Medicine found that people who guzzle diet soda daily have a 43 percent higher risk of vascular events—such as stroke and heart attack—than people who don’t drink diet soft drinks. However, light diet soda drinkers—those who sipped diet soft drinks somewhere between once a month and six a week—were not more likely to suffer vascular events.So what can you do if you’re truly hooked on diet soda? While drinking water is the best way to quench your thirst, the truth is, that doesn’t always make for the most appetizing replacement. “For most people,” says Sporny, “the weight of water isn’t great enough to make it appealing to them. When fluid becomes a bit heavier, it’s more palatable.”That’s why both Sporny and Lin recommend seltzer water as your swap of choice. Carbonation is a naturally calorie-free way of putting some extra oomph in your glass. If you still want some sweetness to your drink, mix a bit of fruit juice with your seltzer and sip away.MORE: Diet Soda Boosts Risk of Heart Attack & Stroke